One possible way to create a zoom simulation using RAMSES is using the [HAST](https://bitbucket.org/vperret/hast/) code, which is a set of tools for selecting a candidate halo in a "unigrid" cosmological simulation to be zoomed later, and also for acquiring various information about this halo. All the initial conditions (unigrid and zoom) are supposed to be generated using [MUSIC](https://www-n.oca.eu/ohahn/MUSIC/index.html). A step by step guide can be found [here](https://bitbucket.org/vperret/hast/wiki/Home).